1. Field of Invention:
The present invention relates to artificial ventricles for use as part of a total artificial heart for implantation within a living being as part of its circulatory system. More specifically the present invention relates to an artificial ventricle which can be easily positioned and surgically implanted within the patient.
2. Prior Art:
The successful advent of the total artificial heart has offered new options for extending life of patients who are awaiting heart transplants or to provide a permanent replacement if a donor heart is not available. The need for such artificial hearts is critical in view of the limited availability of donor hearts (no more than 2,000 donor hearts are available per year) as compared to the patient demand for such transplants exceeding 33,000 per year in the United States alone. Whereas terminal patients who might otherwise have little hope for survival because of the great shortage of donor hearts have little hope except as may be provided by total artificial heart systems, greatly increased attention has been given to improving such devices to overcome the myriad of technical hurdles associated with mechanically replicating the structure and performance of the natural human heart. One of the greatest challenges in connection with improving this field of technology is reduction in size of the total artificial heart and its supporting component structure to adapt to the limited physical space within the chest cavity and for its implantation. The implantation procedure requires physical space to suture the artificial atrium, aorta and pulmonary artery to their natural counterparts. Failure to achieve proper suturing of junctions with the soft tissue of the circulatory system would be a major cause of hemorrhage (bleeding), breaking of suture lines causing dehiscence and thrombogenesis.
Unfortunately, a mere reduction in size of the artificial ventricle is not a solution to the problem. Minimum stroke volumes are required to maintain adequate blood flow to support life systems of the human body. Accordingly, the artificial heart must have sufficient cavity volume to enable adequate stroke volume for pumping blood through the circulatory system. To date, man's technology has been unable to duplicate the compactness, the softness and pliability and efficiency of the natural human heart with total artificial heart systems.
The Jarvik-7 total artificial heart is characteristic of prior art devices within this general field of technology. Specifically, their ventricles are of singular construction and include a rigid casement which includes a blood flow compartment and pumping compartment. These compartments are separated by one or more diaphragms which alternately extend and contract in response to a fluid drive system which alternates between positive and negative pressure within the pumping compartment. Because of the difficulty of suturing the artificial heart and attached valve structure within the chest cavity, quick-connect couplers were developed to be sutured to the atrium, aorta and pulmonary arteries before attachment of the artificial ventricles. This provided some room for the surgeon to work within the limited chest cavity space. Once the quick connect couplers were sutured to the soft tissue of the circulatory system, the artificial ventricles would then be quick coupled at their valve openings or with their artificial atria, aorta and pulmonary artery to their natural counterpart within the chest cavity.
Unfortunately, special equipment is required for testing the suture lines. After connection of the rigid ventricle, these suture lines are difficult to reach. The quick connects enhance the risk of thrombogenesis at the quick coupling sites and even more so if the valves are incorporated in them.
Because of these and other limitations, widespread use of the total artificial heart is still limited. What is needed is artificial ventricles which are more easily implanted and which do not impose the severe spacial restraints which result from the rigid artificial hearts of the prior art.